The invention relates to a device for automatic measurement of measuring fields.
The invention relates to a device for an automatic photoelectric measurement of measuring fields being provided on a sheet or strip type, opaque or transparent original. Such devices which are commonly named automatic strip readers are used, for example, in the photographic industry for a routine control of wet chemical device components on one hand and for the control of the settings of a photographic copy device (printer) on the other hand.
For the control of wet chemical device components, film or paper developing baths, respective film chemistry or paper chemistry strips are measured. These strips already underwent a standardized exposure at the respective film or copy paper manufacturer, and they contain a different arrangement of various measuring fields which differ from manufacturer to manufacturer. The operator of the wet chemical units develops the strips in more or less regular intervals in the respective film or paper developing units. The developed film or paper strips are photometrically analyzed using a hand densitometer or the mentioned automatic strip reader, whereby the determined measurement data are compared to the target data of the manufacturer. Depending on the determined comparative results, the developing baths are refreshed or filled up, renewed, or maintained unchanged. To control the settings of a photographic printer, one or several standard negatives are projected onto the photographic paper which is developed using a standardized and tested chemistry. The developed pictures are again photometrically analyzed and the determined measurement data are compared to the target data of the manufacturer. In dependence upon the determined comparative values, the settings of the printer can be corrected or maintained. Further details for this and examples for typical measurement strips are found in U.S. Pat. No. 5,402,361 and U.S. Pat. No. 5,118,183, the disclosures of which are hereby incorporated by reference in their entirety.
A strip reader of this kind is described in U.S. Pat. No. 5,519,210, the disclosure of which is hereby incorporated by reference in their entirety. It includes a housing having an insertion slit arranged on its front side for a test stripxe2x80x94film or paper to be measured. A transport system is disposed within the housing in order to draw the supplied test strip in through the insertion slit and to advance it along a transport path and in doing so to guide it in a defined manner. In the vicinity of the transport path, a densitometric measurement arrangement is provided which can be operated in both, transmission and remission mode, so that transparent (film) and opaque (paper) test strips can be equally measured. While the test strip is inserted, the measurement arrangement photoelectrically scans subsequent measuring fields in the direction of the transport path and transfers the electrical signals thus obtained to a controller which calculates digital measuring data therefrom which represent the (color) density of the scanned measuring fields on the test strip. In addition, the densitometric measurement arrangement is adjustable transverse to the transport direction of the test strip to allow the measuring of test strips having a two-dimensional array of measuring fields, so that the scanning can be carried out sequentially manner in several parallel tracks. The motion and function sequences are carried out under the control of the digital controller. Furthermore, a bi-directional interface connected to the controller is provided through which a data exchange with an external computer can occur, whereby the generated digital measuring data of the individual measuring fields of the test strip can be transferred to the external computer. In the case that the device is to be operated autonomously, it is additionally provided with a suitable keyboard and an optical display unit, which is connected to the controller and operates in concert with the same. After the measuring fields are measured, the test strip is ejected again through the insertion slit.
A further known strip reader is subject of U.S. Pat. No. 5,402,361 and U.S. Pat. No. 5,118,183, the disclosures of which are hereby incorporated by reference in their entirety. These devices are also equipped with densitometric measuring arrangements for the photoelectric measurement of the measuring fields contained on the control strip, but the densitometric measuring arrangements are not laterally adjustable so that the scanning of test strips with a two-dimensional measuring field arrangement is comparatively laborious and only possible by multiply inserting the test strip from the side in an off-set manner. The strip readers presented in these documents are connected to a telephone network by means of a suitable data interface and a modem, and furthermore are connected to a remote computer, for example a central quality control station. The remote computer can retrieve digital measuring data from the strip reader or, for example, can send control commands and messages to the strip reader, whereby the control commands trigger certain functions, and messages can be displayed, for example, on the display of the strip reader.
The densitometric analysis of the test strips which has been exclusively used to date in known strip readers is not sufficient in view of increased demands for quality in modern photographic production lines and color management. It is an object of the present invention to improve a device of the generic type in so far as to allow for a more accurate and dependable analysis of the measuring fields of the test strips, so that better justice can be done to the demands and possibilities of modern photographic high quality production lines and that the device can also be particularly used for color management.
The spectral measurement in accordance with the invention of the measuring fields allows a more accurate and objective evaluation of the same, which in turn allows a more accurate and better adjustment of the individual parts of the photographic production line. The device is particularly suited for use in so-called color management, where measuring strips with very many measuring fields (far above 100) are used and colorimetrically measured with high precision.
In order to also measure very dense transparent originals, an additional densitometric measuring arrangement is provided in accordance with a preferred embodiment. This additional measuring arrangement makes the device more universally applicable.
In accordance with a further advantageous embodiment, the spectral measuring arrangement or the spectral and densitometric measuring arrangements are adjustable laterally to the direction in which the original moves. As a result, an automatic measurement of originals having two-dimensional measuring field arrangements is possible.
Further particularly advantageous embodiments and improvements of the device in accordance with the invention are the subject of the dependent claims.